Perhaps because he, like most people, realizes that life is an ongoing series. What Ayers did and said 40 years ago - when Barack Obama was 7 or 8 years old - was in a very different time. A volatile, angry time when many people felt that drastic responses and solutions were needed.

What were YOU like 40 years ago? (I grant that SOME people become nastier as they age, instead of t'other way 'round.) *g*